Earthmoving machines typically operate in various environments and perform various tasks. Certain tasks require the machine to pull or push heavy loads at low ground speeds and at various inclinations for prolonged periods. Examples of such machines include motor graders, pavers, bulldozers and other types of machines that can shape the earth, as well as machines that carry heavy loads such as trucks. In addition to operating under heavy load conditions, machines can often operate at extreme environments where high ambient temperatures are present.
To provide the required torque capability and to enable efficient and reliable operation, certain earthmoving-type machines are powered by internal combustion engines such as engines operating on diesel, natural gas, gasoline and/or other fuel types. In a typical application, the internal combustion engine is connected to and drives a transmission, which is capable of providing various gear ratios. Machine propel systems, i.e., systems configured for moving the machine along the ground, which can include wheels, tracks or other ground engaging member types, may receive power through the transmission.
Many different transmission types can be used to power machines. In certain applications, continuously variable transmissions may be used because of their flexibility in operating under many different gear ratios. Such capability is advantageous, especially in those machine applications that control engine speed within narrow ranges for efficiency, fuel economy, noise attenuation and other reasons. Thus, for a given engine speed, a continuously variable transmission (CVT) may be adjusted to provide a relatively slow ground speed at high torque and at relatively low engine speeds.
However, machines operating at low engine speeds and at high load, especially in hot ambient environments, have been known to cause overheating in the engine of the machine, especially if operation under such conditions is for prolonged periods. Engine overheating, which can lead to engine failure or seizing, in certain instances, is the result of insufficient cooling provided by an engine cooling system, which depends on active cooling of engine coolant through a radiator to maintain proper engine temperature. As is known from typical applications, engine cooling systems utilize ram air passing over a radiator when the machine is moving to provide convective cooling of the radiator. When the machine is motionless or slow moving, convective radiator cooling is promoted by an engine-operated fan, which may be electrically, mechanically or hydraulically driven.
Known systems address operation under conditions that may lead to engine overheating using passive means, for example, by alerting the operator of the engine overheating condition. If an engine overheating condition is not addressed, known systems include safety measures that can shut down the engine to avoid engine damage due to overheating. Apart from such passive measures, known systems are unable to address machine operation under conditions that can lead to engine overheating. To avoid such conditions, operator knowledge, experience and training are the best methods for avoiding machine damage.